Circuit interrupter having nuisancetripping stop means



May 31, 966 F. L. GELZHEISER 3,254,176

CIRCUIT INTERRUPTER HAVING NUISANCE-TRIPPING STOP MEANS Original Filed Aug. 25. 1960 3 Sheets-Sheet l May 31, 1966 F. L. GELZHEISER 3,254,176

CIRCUIT INTERRUPTER HAVING NUISANCEF-TRIPPING STOP MEANS Original Filed Aug. 25. 1960 3 Sheets-Sheet 2 Fig.5

y 1966 F. L. GELZHElSER 3,254,176

CIRCUIT INTERRUPTER HAVING NUISANCE-TRIPPING STOP MEANS Original Filed Aug. 25, 1960 3 Sheets-Sheet 5 United States Patent cc 3,254,176 7 CIRCUIT INTERRUPTER HAVING NUISANCE- TRIPPING STOP MEANS 7 Francis L. Gelzheiser, Fairfield, Conn., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Original application Aug. 25, 1960, Ser. No. 51,963.

Divided and this application Apr. 12, 1965, Ser. No.

3 Claims. (Cl. 200-88) This application is a division of the copending application Serial No. 51,963, filed August 25, 1960.

This invention relates to electric circuit breakers and more particularly to manually and automatically operable circuit breakers for controlling small and moderate power electric circuits.

An object of this invention is to provide an improved circuit breaker with means for preventing nuisance tripping of the breaker when the breaker is manually operated.

Another object is to provide an improved dependable duplex circuit breaker which is relatively inexpensive and easy to manufacture and assemble.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the fol lowing detailed description when read in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevational view ofone of the interrupting units of a circuit .breaker embodying the principal features of the invention. The interrupting unit is shown in the closed position;

FIG. 2 is a view similar to FIG. 1 except that the parts are shown in the open position;

FIG. 3 is a side elevational view of the other interrupting unit of the duplex circuit breaker, the parts being shown in the tripped position;

' FIG. 4 is an exploded perspective view, on an enlarged scale, of some of the mechanism of the interrupting unit shown in FIGS. 1 and 2 and FIG. 5. is an end view, on a smaller scale, of the assembled duplex circuit breaker.

Certain features of the circuit breakers of this invention are described and claimed in the patents to Francis L. Gelzheiser, Patent No. 3,088,008 and Patent No. 3,110,786.

Referring to FIG. 5 of the drawings, a duplex circuit breaker indicated generally at 9 includes an insulating housing which is composed of two parts, 11 and 13, formingtwo compartments. Each of the parts 11 and 13 is composed of a back portion molded integral with four sides forming an open front. The open front of the part 11 is covered by the back portion of the part 13, and the open front of the part 13 is covered by a cover 15. The three housing parts 11 13 and 15 are held rigidly together by three rivets 17 (FIGS. 1-3).

The housing parts 11 and 13 form two independent compartments housing 'two circuit interrupting units which, except for a line terminal structure that will be described later, are of substantially identical construction and operation, each, for most applications, operating independently of the other. FIGS.'1 and 2 illustrate the closed and open positions respectively of the circuit interrupting unit housed in compartment 13- (FIG. 5). The tripped position of the interrupting unit of the compartment 11 is shown in FIG. 3. The interrupting units illustrated in FIGS. 1-3 are different units in order to more clearly illustrate front mounting means which will be hereinafter described. Since the operation of both of the interrupting units and all of the parts except those that are specifically mentioned to be otherwise are alike,

3,254,176 Patented May 31, 1966 like parts are shown with like reference characters, and the description of the operation of the mechanism of only one of the interrupting units can be applied, unless otherwise mentioned, to both of the units of the duplex circuit breaker.

Referring to FIG. 1 of the drawings, the circuit interrupting unit shown therein comprises a stationary contact 21, a cooperating movable contact 23, a supporting metal frame indicated generally at 25, an operating mechanism indicated generally at 27 and a trip devic'e indicated generally at 29.

The stationary contact 21 is welded, or otherwise attached, to a line terminal 3-1 which has a flange upper portion 32 (FIG. 4) that fits into a slot in the housing part 13. The line terminal 31 is held firmly in place by a stamped-out portion 33 that biases against a projection 34 that is molded integral with the housing part 13. A portion of the line terminal 31 protrudes through an opening 35 (FIG. 5) in the housing part 13. A similar portion of a symmetrically constructed line terminal 37 protrudes through an opening 39 in the housing part 11. Each of the line terminals 31 and 37 is a part of a separate independently functioning circuit interrupting unit. These terminals are resiliently biased to engage opposite sides of a contact member in a load center when the duplex circuit breaker is mounted in operating position. I

The stationary contact 21 cooperates with a movable contact 23 that is welded or otherwise attached to a small flange 40 of a generally C-shaped contact or switch arm 41. Means for operating the switch arm 41 to the open and closed positions comprises an operating member indicated generally at43 having a V-shaped opening 45 herein, which opening receives a projection 47 of the metallic frame 25. The operating member 43 is biased outwardly or upward as seen in FIGS. 13, by means to be hereinafter described, to a position wherein the lower edges of the projection 47 pivotally engage the lower side walls of the V-shaped opening 45. As can be best seen in FIG. 4, the switch arm 41 is bent over at its upper end at 48 and an opening 49 is stamped in the part 48. Depressions 51 are formed in the part 48 on opposite sides of the slot 49. When the parts are in operating position, a projection 53 (FIGS. 4, 6 and 7), molded integral with the operating member43, extends into the slot 49 of the switch arm 41 to position the operating member 43 relative to the switch arm 41, and pivoting portions 55 on opposite sides of the projection 53 of the operating member 43 pivotally engage in the depressions 51 in the switch arm 41. The operating member 43 has a handle portion 57 molded integral therewith which extends through an opening 61 (FIGS. 1-3) in the housing whereby the mechanism may be manually operated to open and close the breaker. Arcuate surfaces 63 on opposite sides of the handle 57 substantially close the opening 61 in all positions of the operating member 43. Motion is transmitted from the operating member 43 to the switch arm 41 when the breaker is manually operated, and, from the switch arm 41 to the operating member 43 when the breaker is automatic-ally tripped open.

The frame 25 supports an insulating pivot 65 (FIG. 4) having shoulders 67 at opposite ends thereof, which shoulders rest within a slot 69 in the frame 25 and a slot 71 in a projection 73 of the frame 25. A trip member 79 is pivotally supported at one end 77 by means of a bight portion which is pivotally supported in a slot 81 in the insulating pivot 65. The other end 82 of the trip member 79 has a latch point 83 which rests on a ledge 85 on an armature 86 to support the trip member in latched position. The armature 86 is part of the trip device 29 which will be described later.

As best illustrated in FIG. 4, the ends 77 and 82 of the trip member 79 are offset, and disposed in a plane which is parallel to a plane in which the main body portion of the trip member 79 is disposed. A spring 88 (FIGS. 1 is connected, under tension, at one end in a slot 89 in the contact arm 41, and at the other end in a slot 91 (FIG. '4) in a projection 93 extending from the trip member 7 9.

The movable switch arm 41 is connected by means of a flexible shunt 95 (FIG. 1) to the free end of a bimetal 97 which is attached, near its other or upper end, to a projection 101 extending out from the supporting frame 25. A terminal conductor 103 is welded or otherwise attached to the upper end of the bimetal 97 to electrically connect the bimetal to a load terminal structure that is indicated generally at 104. The closed circuit through the breaker extends from the line terminal 31 through the stationary and movable contacts 21, 23, the switch arm 41, the flexible shunt conductor 95, the bimetal element 97, the load terminal conductor 103 to the load terminal structure 104. Since the movable switch arm '41 extends downwardly from its pivot, the arc is established adjacent the bottom of the housing in an arc chamber 111, one end of which is connected by a vent passage 113 to an opening in the end of the housing beneath the load terminal structure 104.

The circuit interrupting unit'rnay be manually operated to open and close the contacts by operation of the insulating handle 57. Movement of the handle 57 clockwise, from the position shown in FIG. 1 to the position shown in FIG. 2, carries the upper end of the switch arm 41 to the left of the line of action of the spring 88 whereupon the spring acts to move the contact arm 41 with a snap action to the open position shown in FIG. 2. A projection 109 molded integrel with the housing acts as a limit stop for the movable contact arm during an opening operation. Movement of the operating handle 57 in a counterclockwise direction, from the position in which it is shown in FIG. 2, to the position in which it is shown in FIG. 1 moves the upper end of the switch arm to the right to move the parts to the closed position shown in FIG. 1. Movement of the handle 57 in either direction is limited by the surfaces 115 which strike the housing at either extreme position. The modified knife edge bearings of the pro ection 47 of the frame 25 within the opening 45 of the operating member 43, and of the pivoting portions 55 of the operating member 43 with the depressions 51 of the switch arm 41, encounter little friction and they, therefore, provide for a smooth operating type of mechanism.

The trip device 29 includes the bimetal 97, a U-shaped magnet 117, the armature 86 which is pivotolly supported on the bimetal 97, and a spring 119 which biases the armature in a counterclockwise direction about its pivot. Upon the occurrence of an overload current below a predetermined value, the bimetal element 97 becomes heated, and when it is heated a predetermined amount it deflects to the right as seen in FIG. 1. Due to the engagement of a tail portion 121 of the armature 86 with the bimetal 97, the armature is carried to the right with the bimetal to release the trip member 79.

When the trip inember 79 is released, the spring 88 acts to rotate it clockwise about its pivot 65 until it is arrested when a stop portion 133 thereon strikes the projection 109 of the housing. During this movement, the line of action of the spring 88 moves to the right of the pivot 55, 51 of the switch arm 41, whereupon the spring biases the switch arm in opening direction and moves the switch arm so that the line of action of the force exerted by it on the operating member 43 shifts across the pivot 45, 47 and aetuates the operating member 43 to the tripped position shown in FIG. 3. In order to provide a visual indication that the breaker has been automatically tripped open, movement of the operating member 43 is stopped in an intermediate position (FIG. 3) when a projection 135, molded integral with the operating member 43, strikes the projection 93 which extends from the trip member 79.

Positive separation of the contacts is assured during a tripping operation by the provision of a projection 137 extending from the trip member 79. If the contacts are slow in opening due to sticking,drag or other reasons, the projection 137 engages the inner edge of the switch arm 41, with a swiping action, to start the switch arm in opening direction.

The interrupting unit is trip-free in that it will automatically trip open even though the handle 57 is held in the closed position.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accomplished by moving the operating handle 57 clockwise from the tripped position (FIG. 3), slightly beyond the full open position (FIG. 2).

During this movement, the projection 135 of the operating member 43 engages with the projection '93 of the trip member 79, and the trip member is moved counterclockwise until the latch point '83 thereon is again supported in the latched position on the ledge (FIG. 4) of the armature 86, which position is shown in FIG. 2.

The circuit interrupting unit is tripped automatically and instantaneously by the electromagnet 97, 117, 8 6 in response to overload currents above the predetermined value. Upon the flow of current through the bimetal 97, a magnetic flux, which is induced around the bimetal, takes the path of least reluctance through the magnet 117, across an air gap 139, and through the armature 86. When an overload current above the predetermined value occurs, the pull of the magnetic flux is of such strength that the armature 86 is attracted to the magnet 117 and pivots in a clockwise direction about the bimetal 97. This movement releases the trip member 79, and the contacts are opened in the same manner .previously described in connection with the thermal tripping operation. The features of the trip device 29 are specifically described and claimed in the aforementioned patents to Francis L. Gel-zheiser, Patent No. 3,088,008 and Patent No. 3,110,- 786. For this reason, only a brief description of the trip device is given herein,

A stop portion 157 which is stamped out of and extends from the frame 25, is provided to prevent nuisancetripping of the circuit breaker when the breaker is being manually operated. Without the stop 157, when the breaker is rapidly operated from the closed to the open position, the projection 135, of the operating member 43, hits the projection 93, of the trip member 79, causing the trip member to rotate in a counterclockwise direction, whereupon a portion 159 of the trip member 79 bears against the armature 86 moving the armature in a counterclockwise direction to a position closer to the magnet 117. The parts reach this position only momentarily because the tension of the spring 38 operates quickly to pull the trip member back to the normal latched position shown in FIG. 2'. The armature is biased back to the normal position shown in FIGS. 1 and 2 by means of the spring 119. If the trip member 79 returns before the armature 86 reaches its full normal position, then the trip member does not necessarily reengage with the ledge 85 (FIG. 4) of the armature 86 and, the trip member sometimes drops to effect a tripping operation. This nuisance tripping is eliminated by the stop 157 which positively prevents excess overtravel of the trip member 79 so that the portion 159 of the trip member 79 will not engage and move the armature 86 during manual operation of either of the interrupting units of the circuit breaker.

Since numerous changes may be made in the abovedescribed construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all of the matter contained in the foregoing description or shown in the,

accompanying drawings shall be interpreted as illustra tive and not in a limiting sense.

I claim as my invention:

1. A circuit breaker comprising a pair of cooperable contacts operable between opened and closed positions, an operating mechanism for operating said contacts, said operating mechanism comprising a latched pivotally sup ported trip member, trip means latching said trip member, upon the occurrence of overload currents above a predetermined value through said circuit breaker, said trip means operating automatically to release said trip member whereupon said trip member pivotally moves in a first direction to operate said operatingmechanism to open said contacts, handle means operable when said trip member is latched to operate said operating mechanism to open and close said contacts, and a stop member positioned to stop movement of said trip member in a second direction opposite said first direction when said trip member is latched and said handle means is operated to effect operation of said contacts.

2. A circuit breaker comprising an insulating housing having opening means therein, a pair of cooperable contacts supported within said housing and operable between opened and closed positions, a spring operating mechanism supported within said housing for operating said contacts, said spring operating mechanism comprising a trip member pivotally supported at one end thereof and latched at the other end thereof, trip means supported within said housing and latching said other end of said trip member, upon the occurrence of overload currents above a predetermined value through said circuit breaker said trip means operating automatically to release said other end of said trip member whereupon said trip member effects a tripping operation pivot-ally moving in a first direction to operate said spring operating mechanism to open said contacts, handle means protruding through said opening means in said housing and being externally manually operable when said trip member is latched to operate said spring operating mechanism to open and close said contacts, and a stop member positioned within said housing to stop movement of said trip member in a second direction opposite said first direction to thereby prevent nuisance tripping operations when said trip member is latched and said handle means is manually operated to effect operation of said contacts.

3. A circuit breaker comprising an insulating housing having opening means therein, a pair of cooperable contacts disposed within said housing and operable between opened and closed positions, a metallic supporting member supported within said housing, an operating mechanism comprising a spring member for operating said contacts, said operating mechanism comprising a trip member pivotally supported at one end thereof on said supporting member and latched at the other end thereof, trip means supported within said housing on said supporting member and latching said other end of said trip member, upon the occurrence of overload currents above a predetermined value through said circuit breaker, said trip means operating automatically to release said other end of said trip'member whereupon said spring member pivotally moves said trip member in a first direction to effect opening of said contacts, handle means supported on said supporting member and protruding through said opening means in said housing, said handle means being externally operable when said trip member is latched to operate said spring member to open and close said contacts, and a projection of said supporting member positioned to stop movement of said trip member in a second direction opposite said first direction to prevent undesirable release of said trip member when said trip member is latched and said handle means is operated to effect operation of said contacts.

No references cited.

BERNARD'A. GILHEANY, Primary Examiner. 

1. A CIRCUIT BREAKER COMPRISING A PAIR OF COOPERABLE CONTACTS OPERABLE BETWEEN OPENED AND CLOSED POSITIONS, AN OPERATING MECHANISM FOR OPERATING SAID CONTACTS, SAID OPERATING MECHANISM COMPRISING A LATCHED PIVOTALLY SUPPORTED TRIP MEMBER, TRIP MEANS LATCHING SAID TRIP MEMBER, UPON THE OCCURRENCE OF OVERLOAD CURRENTS ABOVE A PREDETERMINED VALUE THROUGH SAID CIRCUIT BREAKER, SAID TRIP MEANS OPERATING AUTOMATICALLY TO RELEASE SAID TRIP MEMBER WHEREUPON SAID TRIP MEMBER PIVOTALLY MOVES IN A FIRST 